Automatic slack-adjuster.



No. 728,443. PATENTED' MAY 19, 1903'.

F. L. CLARK. AUTOMATIC SLACK ADJUSTER.

' 3 SHEETS-SHEET 1.

APPLICATION FILED SEPT. 6, 1901 1m MODEL.

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THE mains rzrzn co, wow-m No. 728,443. PATENTBD MAY 19,1903.

F. L. CLARK. AUTOMATIC SLAGK;ADJUSTER.

APPLIOAT ION FILED SEPT. 6, 1901.

K0 MODEL.

a SHEETS-SHEET a.

' lulu "li n c UNITED STATES Patented May 19, 1903.

PATENT 7 OFFICE. I

FRANCIS L. CLARK, OF PIT'ISBURG, PENNSYLVANIA,ASSIGNOR TO THE AMERICAN BRAKE COMPANY, OF ST. LOUIS, MISSOURI, A CORPORA- TION. OF MISSOURI.

AUTOMATIC SLACK-IADJUSTER.

SPECIFICATION formingpart of Letters w s No. 728,443, dated May 19, 19cc. Application filed September 6, 1901. Serial No. 74,537. (No model.)

To all whom, it may concern:

Be it known that I, FRANCIS L. CLARK, a citizen of the United States, residing at Pittsburg, county of. Allegheny, State of Pennsyl Vania, have invented or discovered a certain new and useful Improvement in Automatic Slack-Adj usters for Brakes,0f which improvement the following is a specification.

My invention relates to slack-adjusters for railway-brakes, and particularly to that class of brakes in which a fluid-pressure brake-cylinder is employed; and the object of my-invention is to provide an adjustable connection between the brake-piston and the brakerigging whereby the slack of the brake-rigging, due to the wear of the brake-shoes and other causes, will be automatically taken up, so as to maintain a practically constant and uniform travel of the brake-piston. I

My invention consistsin providing, in combination with the brake-piston, an extensible mechanism adapted to receive the push-bar of the brake-rigging; and it also consists in forming said extensible mechanism of a tu-' bularadjusting-screw connected to the brakepiston through'a ratchet-nut and pawl mechanism,whereby the position of the screw with respect to the brake-piston may be automatically adjusted. My invention further consists in certain combinations and arrangement of parts,' all as hereinafter more fully set forth.

In the accompanying drawings, Figure 1 is a longitudinal section of a brake-cylinder and my improved construction applied thereto;

Fig. 2, a plan view of the rear head of a brakecylinder and the slack-adjusting mechanism, aportion of the cam-plate being broken away to more clearly show the construction; Fig. 3, an end view, the hand-wheel being removed and a part of the outer not being broken away to show the ratchet-nut; Fig. 4, a transverse section taken on the line'w 0c of Fig. 1; Fig. 5, a vertical section showing a modified form of brake-cylinder and slack=adjusting mechanism; Fig. 6, a horizontal section taken on the line y y of Fig; 5; Fig. 7, a vertical section taken on the line 2 z of Fig. 6; Fig. 8, a vertical section of the lower end portion of the brake-cylinder, showing the key mechanduring the automatic adjustment of the slack; Fig. 9, a fragmentary perspective view showing the connection between the same'plate and the ratchet-ring, and Fig. 10 a detail sectional view taken on the line to w of Fig. 8.

Referring now moreparticularly to Sheet 1 of the drawings, the brake-cylinder 1, piston 2, and spring 3 (shown in Fig. 1) may be of thefordinary or any preferred construction.

The piston is provided with the hollow or tubular"piston rod 4, which extends out through the rear head 7 of the brake-cylinder and in which is located the hollow screw 5, adapted to receive the end of the thrust-bar 19 of the brake-rigging. On the hollow piston-rod is located the split sleeve or bush 6, which is made in two parts. and securely clamped onto the red by means of bolts 8. This sleeve is provided with a key 9, which works in a corresponding notch or seatin the cylinder-head 7 and prevents rotary'movef-ment- 'of 'the sleeve and piston-rod. The

[ratchet-nut to prevent a backward rotation of the same. Springs 27 and 28 may be provided to force the respective pawls into engagement with the teeth of the ratchet-nut. The ring is held on the ratchet-nut by a nut 15, and the projecting end of the hollow screw is provided with a hand-wheel 18, by means of which the screw may be returned to its inner position when it becomes necessary to reset the mechanism. In order to prevent the screw from turning during the automatic operation of adjustin'gihe slack, I provide a key 20, which is carried by the trigger-lever 22, pivoted to the lugs 21 on the split sleeve 6, the key extending through the openings in 0 ism for preventing the rotation of the screw 1 the sleeve and piston-rod and into the groove 24, formed in the thread of the hollow screw 5. A spring 23 normally presses the key 20 into the said groove; but when the screw is to be turned back by hand to reset the device the trigger-lever is pushed'in against its spring to raise the key outof the groove 24 and allow a free adjustmentof the screw by means of the hand-wheel 18. The pawl-ring 14 has a projection or pin 16, extending into the cam slot or groove 29 of the cam-plate 10. This camplate maybe supported in position byanyconvenient means; but as a preferred construction I have shown the same secured to the cylinder-head 7 by means of a cap-screw 2, passing through a slot 11 in the cam-plate, which allows for theadjustment of the position of the cam-groove with respect to the'brake-cylinder. The cam-plate is so adjusted that the pin 16 reciprocates in the straight portion of the groove during the normal travel of the brakepiston; but when, owing to the wear of the brake-shoes and stretching of the brake-rigging, the travel of the brake-piston becomes greater than desired the projection or pin 16 of the pawl-ring enters the inclined orcurved portion of the cam-groove and turns thering upon the ratchet-nut, thus carrying the pawl 17 backward over one or more teeth of the ratchet-nut, according to the length of the stroke of the brake-piston. Then when the brakes are released and the piston-spring moves the parts positively back to release position the ratchet-nut will be rotated forward one or more notches, thus adjusting the hollow screw outward toward the push-bar and taking up the slack. The pawl 25,which is pivoted on the non-rotatable split sleeve 6 and is in constant engagement with the teeth of the ratchet-nut, prevents the ratchet-nut from turning during the outward movement of the piston, and this is an important feature, since if the ratchet-nut should rotate with the pawl-ring on the outward movement of the piston the slack would be increased instead of diminished. It will also be noticed that the adjusting mechanism is directly secured to the hollow piston-rod, so that it moves positively with the brake-piston, and the operation of taking up the slack is not dependent upon the mere relaxation of the brake-rigging, but is positively performed by the force of the spring of the brake-piston. This construction forms what is practically an extensible hollow piston-rod secured to the brake-piston and adapted to receive the loosely-fittin g push-bar of the brake-rigging.

In Figs. 5 to 10 of the drawings I have shown a compact form of my invention, in which all the parts of the adjusting mechanism are located inside the brake-cylinder, and such a construction is adapted to be used when it is necessary to economize the space occupied by the brake cylinder. In this modified construction the split sleeve 6 is secured directly to the piston by flanges and screws orother means and has a projection 9, extending into the groove formed by the two guide-lugs 30, carried by the inner surface of the rear cylinder-head 7 The piston 2 of the brake-cylinder 1 may be provided with a cylindrical recess 31 in its rear face in line with the opening of the split sleeve 6, through which extends the hollow adjust' ing-screw 5. The ratchet-nut 13 is internally threaded to engage the threads of the adjusting-screw and has a rim and groove forming a rotary bearing in' the split sleeve 6", which prevents any longitudinal movement of the ratchet-nut relative to the piston. On the ratchet-nut is rotatably mounted the pawl-ring 14, carrying the spring-pressed pawl 17*, pivoted on the lug 32, while the fixed spring-pressed pawl 25 is pivotally supported on the lug 26 of the split sleeve 6, and both ,pawls engage the teeth of the ratchet-nut, as in Figs. 1 to 4:. The rear head 7 of the brake-cylinder is formed with an inner cylindrical extension 37, outside of which is an annular space for the spring 3, and the rear end of the cylinder-head is provided with an opening 36 for the triggerlever 22 and a lug 33, having a slot through which the key 20 extends into the groove or key-seat 24: of the adjusting-screw 5. The trigger-lever extends through the opening 36 between lugs 34 and bears at one point against the end of the cap-screw 35, which carries the spring 23, that normally holds the key 20 in engagement with the keyseat 2i and prevents rotary movement of the adj usting-screw. On the ratchet-nutis pinned or otherwise secured the washer 15, the outer perimeter of which is provided with a projecting lug 38, adapted to engage the inner end of the trigger-lever when the latter is operated to withdraw the key 20 from the groove 24: of the adjusting-screw. When it becomes necessary to reset the adjustingscrew, the outer end of the trigger'lever may be readily raised, withdrawing the key 20 from its seat in the adjusting-screw, and at the same time the inner end of the triggerlever bears upon the outer perimeter of the washer 15, so that the lug 38 will engage the trigger-lever and prevent the rotation of the washer and ratchet-nut when the screw is turned back to its inner position by means of the hand-wheel. The operation of this form of my device in automatically taking up the slack is substantially the same as that already described with reference to Figs. 1 to 401: the drawings; The cam-groove 29 in the camplate is so formed that an excessive movement of the brake-piston results in the backward rotation of the pawl-ring and pawl 17 on the teeth of the ratchet-nut. Then upon release of the brakes the ratchet-nut is rotated on the adjusting-screw, and since the latter is prevented from turning it will be adjusted outward to eliminate the slack of the brake-rigging. It will be seen that this is substantially the same construction as that shown on Sheet 1 of the drawings-that is, it constitutes an extensible hollow piston-rod comprising a hollow adjusting screw connected to the brake-piston through a pawland-ratchet mechanism, whereby the position of the screw with respect to the brake-piston may be adjusted.

Having now described my invention, what I claim'as new, and desire to secure by Letters Patent, is

1. A brake-piston having a hollow pistonrod formed in sections, one of said sections being adjustable and adapted to receive the push-bar of the brake-rigging.

2. Thecombination of a brake-piston havin g an extensible rod secured thereto adapted to receive the push-bar of the brake-rigging,

, and means for adjusting the length of the rod.

3. In a brake slack-adjuster, the combination with a brake-piston of a hollow adjusting-screw adapted to receive the push-bar of the brake-rigging, said screw being connected to the piston through a ratchet mechanism whereby the position of the screw relative to I the brake-piston may be adjusted.

4. In a brake slack-adjuster, the combination with a brake-piston having an extensible rod secured thereto including an adjustingscrew, of a ratchet-nut for the screw, and means for preventing the backward rotation of the ratchet-nut.

5. In a brake slack-adjuster, the combination of a brake-piston, an adjusting-screw secured thereto and adapted to operate the pushbar of the brake-rigging, a ratchet-nut, a pawl for giving a forward rotation to the ratchetnut, and another pawl for preventing a backward rotation of said nut.

6. In a brake slack-adjuster, the combination with a brake-piston having an extensible rod including an adjusting-screw, of a ratchetnut and pawl mechanism for adjusting the screw, and a key for preventing the rotation of the screw.

1 therewith, an adjusting-screw, means for preventing rotation of the sleeve, and a ratchetnut rotatably connected to said sleeve for adjusting the screw.

8. In a brake slack-adjuster, the combination with a brake-piston of a sleeve movable therewith, an adj usting-screw, a ratchet-nut for the screw rotatably mounted in the sleeve, means for preventing rotation of the sleeve, and a pawl carried by the sleeve for preventing backward rotation of said nut.

9. In a brake slack-adjuster, the combination with a brake-piston having an extensible rod including an adjusting-screw, a ratchetnut for adjusting the screw, a key for normally preventing rotation of the screw and hand-operated means for withdrawing the key and turning the screw back to its original position in the nut.

10. In a brake slack-adjuster, the combination with a brake-piston having an extensible rod including a ratchet-driven screw, of a key en gaging the screw to prevent rotation'there- 7c of, and a trigger-lever for operating said key.

11. In a brake slack-adjuster, the combination of a brake-piston having a tubular rod and a split sleeve clamped on said rod, of an adjusting-screw in said tubular rod and a ratchet-nut for adjusting said screw.

12. In a brake slack-adjuster, the combination of a brake-piston, a sleeve movable therewith, means intermediate the sleeve and cyl- 1 inder-head for preventing rotation of the'8o.

sleeve, an adj usting-screw and a ratchet-nut engaging said screw and rotatably mounted in said sleeve.

13. In a brakeslack-adjuster, the combination of a brake-cylinder having an extensible hollow piston-rod formed in sections, one section comprising a hollow adjusting-screw, of a ratchet nut for said screw, a pawl-ring mounted on said nut and having a pawl engaging the teeth of the ratchet-nut, and a camplate adapted to oscillate thepawl-ring upon excessive travel of the brake-piston.

In testimony whereof I have hereunto set my hand.

FRANCIS L. CLARK.

Witnesses:

J As. B. MACDONALD, R. F. EMERY. 

